I am NOT a happy camper right now and I've already ordered a replacement.
Now I'll have to guess the length of the last couple of rides - 20Ks for Pancakes seems about right, and 50 for the ride to Ballajura and back. These are probably underestimates - it would be realistic to assume that Hepburn Ave from the Freeway to Alexander Dr is at least 8 - 10 Km each way - but if I'm guessing I'd rather be guessing low.
Of course, I'd rather not be guessing at all.